Context. Shuangbai San is a Chinese herb preparation used externally to treat pain. There have been few randomized controlled trials addressing the safety and usefulness of Shuangbai San, such as its effect on pain relief and quality of life (QOL) improvement. Objectives. This study was conducted to evaluate the effect of Shuangbai San on relieving pain and improving QOL in primary liver cancer patients with cancer pain. Methods. A total of 134 primary liver cancer patients with mild pain (numerical rating scale [NRS] #3), either locally in the liver or in the upper abdomen, were enrolled and randomly allocated to the group receiving Shuangbai San or the control group (receiving placebo). The primary outcome measures were the NRS score and QOL scales, including the QOL scale for patients with liver cancer, version 2.0 and the European Organization for Research and Treatment of Cancer QOL Questionnaire-C30. The secondary outcome measures included the Karnofsky Performance Status score, blood indicators, and liver and kidney function before and after treatment. Results. The NRS scores decreased more significantly in the Shuangbai San group than in the placebo group (P < 0.05) at the corresponding time points. The changes in the scores for the physical function, psychological function, and symptoms/adverse effects domains of the QOL scale for patients with liver cancer, version 2.0 and the physical, emotional, and cognitive domains of the European Organization for Research and Treatment of Cancer QOL Questionnaire-C30 were significantly greater in the Shuangbai San group than in the placebo group (P < 0.05). The changes in the scores for the other domains were not significantly different (P > 0.05). Conclusion. The use of Shuangbai San can relieve mild pain in liver cancer patients and improve their QOL. (C) 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.